Kenworth and peterbilt are both owned by paccar. I've driven both of these truck in real life and they are both really nice. mostly looks really seperates them but when optioned they arent a whole lot different
I've always preferred the dash layout of the Kenworth, so it gets my pick. You should be able to spec the trucks to be exactly the same otherwise; gear ratios, engines, and transmission. PACCAR owns both Kenworth and Peterbilt.
You're from Finland so it's kindof like Skoda vs Volkswagen.